a ppt on mutation

1. Presented by :-
Rajesh Kumar(152122028)
Raju Kumar Singh(152122029)
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3. Mutation
Mutation is a change of the nucleotide sequence of the
genome of an organism, virus, chromosomal DNA and
other genetic element.
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• Mutations may be harmful.
• Mutations may be beneficial.
• Mutations may have no effect on the organism.

4. Types of Mutation
• Substitution
• Insertion
• Inversion
• Deletion
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5. Substitution
A substitution is a mutation that exchanges one base for
another (i.e., a change in a single "chemical letter" such as
switching an A to a G).
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6. Insertion
Insertions are mutations in which extra base pairs are
inserted into a new place in the DNA.
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7. Inversion
• An inversion is a chromosome rearrangement in which
a segment of a chromosome is reversed end to end.
• An inversion occurs when a single chromosome
undergoes breakage and rearrangement within itself.
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9. Deletions are mutations in which a section of DNA is lost, or
deleted during DNA replication.
Deletion
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10. A mutation can occur spontaneously or induced by
chemicals or radiations.
Spontaneous mutations on the molecular level include:
Tautomerism - A base is changed by the repositioning of a
hydrogen atom.
Causes of Mutation
Spontaneous Mutation
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12. Depurination - Loss of a purine base (A or G).
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Deamination - is the removal of an amine group from a
nucleotide.
Changes a normal base to an atypical base;
C → U,

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Replacement of a Purine base with another Purine or
pyrimidines with another pyrimidines.
Replacement of a purine with pyrimidines or vice versa.
Transition -
Transversions -

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16. Induced mutation are those resulting from exposure of organism to
mutagenic agents such as ionizing radiation UV light or various
chemical.
Induced mutations on the molecular level can be caused by Chemicals-
•Hydroxylamine NH2OH
•Base analog i.e., Brdu
•Alkylating agents
•DNA cross linkers
•Oxidative Damage
•Nitrous Acids
Induced Mutation
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18. e.g., X-rays, UV
Ionizing radiation breaks covalent bonds including those in
DNA and is the leading cause of chromosome mutations.
Ionizing radiation has a cumulative effect and kills cells at high
doses.
UV (254-260 nm) causes purines and pyrimidines to form
abnormal dimer bonds and bulges in the DNA strands.
Radiation
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20. Mutation in
Humans
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21. Down Syndrome
• Also known as trisomy 21, is a genetic disorder
caused by the presence of all or part of a third copy
of chromosome 21.
• It is typically associated with physical growth delays,
characteristic facial features and mild to moderate
intellectual disability.
• The average IQ of a young adult with Down
syndrome is 50, equivalent to the mental age of an 8
or 9 year old child. 21

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23. Edward’s syndrome
• Also known as Trisomy 18 [T18] is a chromosomal
disorder caused by the presence of all or part of an extra
18th chromosome.
• Named after John Hilton Edwards, who first described
the syndrome in 1960.
• Many parts of the body are affected. Babies are
often born small and have heart defects. Other features
include a small head, small jaw, clenched fists with
overlapping fingers.
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25. Patau syndrome
• It is a syndrome caused by a chromosomal
abnormality, in which some or all of the cells of the
body contain extra genetic material from
chromosome 13.
• The extra genetic material from chromosome 13
disrupts the normal course of development, causing
multiple and complex organ defects.
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27. We are very thankful to Dr. Lal Mohan Kundu Sir
for giving us this opportunity.
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